Please refer to FIG. 1(a), it shows the block diagram of the isolated mechanical power source voltage regulator of the prior art. The isolated mechanical power source voltage regulator 1 includes an isolated transformer 11, a relay switch 12, and an input voltage detecting circuit 13 as shown in FIG. 1(a). The input voltage detecting circuit 13 is employed by the isolated mechanical power source voltage regulator 1 to detect an input voltage. According to the value of the input voltage, a trigger signal is sent out by the input voltage detecting circuit 13 to start the relay switch 12. The relay switch 12 is employed to change the turn ratio of the isolated transformer 11 so as to provide a stable output voltage.
Please refer to FIG. 1(b), it shows the block diagram of the non-isolated mechanical power source voltage regulator of the prior art. The non-isolated mechanical power source voltage regulator 2 includes a self-coupled transformer with multiple-outputs 21, a relay switch 22, and an input voltage detecting circuit 23 as shown in FIG. 1(b). The input voltage detecting circuit 23 is also employed by the non-isolated mechanical power source voltage regulator 2 to detect an input voltage. According to the value of the input voltage, a trigger signal is sent out by the input voltage detecting circuit 23 to start the relay switch 22. The relay switch 22 is employed to change the turn ratio of the self-coupled transformer with multiple-outputs 21 so as to provide a stable output voltage.
According to the above descriptions, changing the turn ratios of the transformers are employed to stabilize the voltage by both of the mechanical power source voltage regulators 1 and 2. Therefore, this kind of power source voltage regulators have the following disadvantages:                (a) The system responses of the mechanical power source voltage regulators are relatively slow and the output voltage modulating rates are relatively high;        (b) Since a transformer with a relatively huge volume is needed by each of those mechanical power source regulators, the power densities of those power source voltage regulators are relatively low; and        (c) The voltage values at the primary windings of the transformers of those mechanical power source voltage regulators are at the commercial power levels no matter they are isolated or non-isolated.        
Please refer to FIG. 2(a), it shows the schematic circuit diagram of the first electronic power source voltage regulator of the prior art. The first electronic power source voltage regulator 3 is an electronic circuit including at least one electronic switch 31, at least one resistor 32, at least one capacitor 33, and at least one inductor 34 as shown in FIG. 2(a). The high frequency electronic switching techniques are employed to provide a stabilized voltage.
Please refer to FIG. 2(b), it shows the schematic circuit diagram of the second electronic power source voltage regulator. The second electronic power source voltage regulator 4 is an electronic circuit including at least one electronic switch 41, at least one resistor 42, at least one capacitor 43, and at least one inductor 44 as shown in FIG. 2(b). The high frequency electronic switching techniques are employed to provide a stabilized voltage.
The above-mentioned electronic power source voltage regulators have the following disadvantages:                (a) The phases of output/input voltages of those electronic power source voltage regulators have the phase shift, and the phase shift is related to the status of the current on the load of the apparatus, thus the bypass route between the input and the output terminals of those electronic power source voltage regulators can not be designed so as to result in the decreasing of the reliability of the system;        
There is no DC-link connecting route in any of the above-mentioned electronic power source voltage regulators, thus a battery can not be added inside such a regulator so as to provide a redundant power source when the commercial power has a significant voltage difference.
Keep the drawbacks of the prior arts in mind, and employ experiments and research full-heartily and persistently, the electronic power source voltage regulator with the UPS function is finally conceived by the applicants.